Sanctions against bankers deemed responsible for the financial crisis could include more legal action abroad, as the UK authorities struggle to bring prosecutions, lawyers say.

The lack of activity by the FSA, which last year conducted its first prosecutions for insider dealing, could be mitigated by extraditions to the US where prosecutors have been more active in investigating banks and senior executives.

"US prosecutors regard non-US participants in 'white collar' crime as fair game and have been clear in sending messages to foreign executives that they are not beyond US law," said Luke Tolaini, a senior UK lawyer on financial crime.

"The response to market issues is much more likely to involve criminal proceedings in the US than here ... they also have a very high conviction rate, largely because of their free use of plea agreements."

Plea agreements allow those charged with fraud to have their sentence reduced for admitting lesser offences. They are not yet recognised under UK law, despite being strongly endorsed by lawyers and politicians including the attorney general, but are under consideration.

US authorities have investigations underway against some of the biggest names in its financial industry, including Washington Mutual, Freddie Mac, Fannie Mae and AIG. Shareholder groups are also more likely to resort to class action lawsuits in the US against misconduct at companies.

The FSA has been criticised for a "light-touch" approach to market misconduct offences. "We are prepared to bring more criminal prosecutions to achieve our goal of credible deterrence," a spokesman said, adding that it had "cases in the pipeline".

"There is a lot of pressure on the regulator to come down hard on people who have misbehaved, and regulatory action has not delivered a sufficient deterrence," said Carlos Conceicao, partner at law firm Clifford Chance.

The Serious Fraud Office, which is also responsible for prosecuting financial crime in the UK, was described recently by US prosecutor Jessica de Grazia as suffering from "startlingly low productivity and convictions rates compared to its New York counterparts".

In 2007-08, the SFO conducted just seven trials in the year and struggled with the complexity and length of trials against those accused of involvement in corporate fraud, with a 68% rate of conviction.

However, experts predict that as the banking crisis continues to deepen, more financial crime will come to light.

"When the economy suffers a downturn, frauds that are sitting in balance sheets tend to become exposed," Tolaini said. "It becomes harder for companies or individuals to cover them up."

Shareholders are also demanding accountability through financial measures such as "claw-back" schemes, which retain a portion of the bonuses paid out to investment bankers unless certain conditions are met. "At times like this, when the public are disillusioned with bankers walking off with massive packages, we are likely to see an increase in these measures," said Tetsuya Ishikawa, a former investment banker and author of How I Caused the Credit Crunch.